The principal objective of this research proposal is to elucidate the biochemical mechanism at the enzymatic and cellular levels for the methylation of specific basic amino acid residues in contractile proteins, particularly actin and myosin, and to explore the problem of the functional significance of methylated residues in the highly specialized proteins. The proposed research will include: 1) an investigation of the enzyme(s) catalyzing the methylation of the basic amino acid residues in the myofibrillar proteins of chick skeletal muscle, including characterization of the protein methylase system, the properties of the recognition site on the acceptor molecules, and the relationship of this system to other protein methylases; 2) an investigation of methylation reactions in skeletal muscles of genetically dystropic chicks; 3) an investigation of the occurrence of an general characterization of the contractile protein methylation system in plasmodia of the myxomycete, Physarum oxysporum; 4) and investigation of the temporal relationship between the biosynthesis of myosin and the methylation of 3-methylhistidine and N-methyllysine residues in myosin using pulse-labeling techniques in monolayer cultures of chick embryonic skeletal muscle.